They aren't jounin level. They had a tough time with two jounins. They're more like hyped up chunins. They've got the second level curse seals and some advanced jutsus, and a bit more experience than the leaf genins with their special abilities and handful of advanced justus. All in all, a pretty challenging fight, but these four Sound nins aren't that far beyond the Leaf group chasing them. Three (four counting Akamaru) is a pretty even fight, probably.